All-electrical detection of spin-coherent trap state dynamics at the Si/SiO2 interface

Dielectric interfaces critical for metal–oxide–semiconductor electronic devices possess spin-coherent trap states that can behave as quantum sensors of small magnetic fields or, through spin noise, contribute to the spin decoherence of electronic quantum bits (qubits). The existence of small numbers of such traps can be electrically detected through spin-dependent recombination current; however, the interpretation of such measurements is only now possible after the publication of a general theory of the phenomena [Harmon et al. Appl. Phys. Lett. 123 251603 (2023)]. This article compares two electrical trap-spin measurement and identification techniques, electrically detected magnetic resonance and the recently observed near-zero field magnetoresistance, with Shockley–Read–Hall trap-assisted recombination current calculations. The bias dependence of these electrical effects provides direct evidence that, for the Si/SiO2 interface, spin mixing of the carriers producing the recombination current occurs via an effective semiclassical hyperfine interaction emanating from the bath of nuclear spins. The results can be generalized to describe the recombination current used as the sensing signal in all-electrical quantum magnetometers, as well as to provide quantitative descriptions of the spin-induced noise relevant for spin qubits near the Si/SiO2 interface.